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3-D printing technology has attracted growing interest of many researchers in the area of antenna design as a new prototyping and manufacturing technology. It is capable of forming arbitrary 3-D structures with lower cost and shorter prototyping time. This paper aims to present a novel methodology to control antenna radiation pattern based on 3-D printing of specially designed dielectric material, which realizes spatially dependent dielectric constants around the antenna. As a proof-of-concept, we propose a design of a quarter-wavelength monopole antenna surrounded by a 3-D-printed polymer structure with an optimized dielectric property distribution. Unlike the conventional donut-shaped pattern of a quarter-wavelength monopole antenna, one-beam and multiple-beam patterns are obtained using a genetic-algorithm-based optimization. Different dielectric constant spatial distributions are realized by changing the ratio of the dielectric to air at the unit cell level in the entire antenna volume. A two-beam monopole prototype is designed, fabricated, and tested. The measurement results demonstrate agreement with the simulation results. The proposed design method enables another degree of freedom for antenna design, which can be extended to other types of antennas. [ABSTRACT FROM AUTHOR]

Dielectric reflectarray antennas are proposed as a promising low-loss and low-cost solution for high gain terahertz (THz) antennas. Variable height dielectric elements are used in the reflectarray designs, which allow for the use of low dielectric-constant materials. Polymer-jetting 3-D printing technology is utilized to fabricate the antenna, which makes it possible to achieve rapid prototyping at a low-cost. Numerical and experimental results are presented for 3 different prototypes operating at 100 GHz, which show a good performance. Moreover the methodology proposed here is readily scalable, and with the current material and fabrication technology, designs up to 1.0 THz can be realized. This study reveals that the proposed design approach is well suited for low-cost high-gain THz antennas. [ABSTRACT FROM PUBLISHER]

In this work, we designed, built, and tested a low-gain 20 dBi Luneburg Lens antenna using a rapid prototyping machine as a proof of concept demonstrator. The required continuously varying relative permittivity profile was implemented by changing the size of plastic blocks centered on the junctions of a plastic rod space frame. A 12-cm (4\lambda0 at 10 GHz) diameter lens is designed to work at X-band. The effective permittivity of the unit cell is calculated by effective medium theory and simulated by full-wave finite-element simulations. The fabrication is implemented by a polymer jetting rapid prototyping method. In the measurement, the lens antenna is fed by an X-band waveguide. The measured gain of the antenna at X-band is from 17.3 to 20.3 dB. The measured half-power beam width is from 19^\circ to 12.7^\circ while the side lobes are about 25 dB below the main peak. Good agreement between simulation and experimental results is obtained. [ABSTRACT FROM PUBLISHER]

An all-dielectric terahertz (THz) horn antenna based on hollow-core electromagnetic crystal structure is designed, fabricated and characterized. Simulation shows that the antenna works above 100 GHz, with better than 30 dB return loss and highly directional radiation pattern. Fabrication of the antenna is done using a THz polymer-jetting rapid prototyping technique. Characterization of the antenna is performed using a THz time-domain spectrometer. Measurement results of the far-field radiation patterns show good agreement with simulation results. [ABSTRACT FROM PUBLISHER]